A clamping device is known according to DE 196 45 778 A1. It has a hollow shaft (clamping arm shaft) that is rotatably mounted in a housing. A clamping element (clamping arm) is fastenable to the shaft. A lever arm (positioning extension) on the shaft provides a toggle lever mechanism. An intermediate element is articulated on one side with the lever arm and on the other side with an axially movable final control element (positioning rod) of a drive element. An inner shaft connected to a hand lever is arranged in the hollow shaft. The inner shaft has a pin element (positioning pin) extending through a link guide (link slot) on the hollow shaft. The pin element can be operationally linked to the toggle lever mechanism. A spring element, which tensions the inner shaft against the hollow shaft in the main axial direction, is positioned outside the housing.
As described in DE 196 45 778 A1, it is possible, using this design to alternately disengage the toggle lever mechanism with the aid of a hand lever or bring it into a so-called top dead center position, and in particular if the final control element of the drive element (pneumatic cylinder, hydraulic cylinder, electric drive, or the like) is movably unobstructed. In particular, the aspect is taken into consideration that in the case of a non-hollow clamping arm shaft, a torque introduction therein is unsuitable to take influence on the toggle lever mechanism.